I agree... an Android App is a must. Someone above asked why we can't just use the web browser. Though I used to feel that way too for all apps, I have found this to be more and more cumbersome the more complicated my passwords get. All the passwords I have created in the last year or so are too tough to type each time I want to log into the Matchup.io site in my Android app. If there was an app I would log in once, and (hopefully) never need to log in again unless I revoke access or change the password for whatever reason. Even just yesterday I was out hiking and wanted to check on my progress of a Labor Day matchup. Since I do not have my password while away from the computer I couldn't check it out. I would assume I am not the only one that uses Matchup less than they would like to because of this.
I think Matchup.io is one of the best apps/projects that has come out in terms of actually using tracker information to challenge, or even just inspire people to get out and get active... no matter what tracker they use. But for me to get my friends, family and followers on board, we need a quick and simple app to check their stats, see their ratings, get excited to do more, and then quickly close the app.
Just my 2 cents of course.